The invention relates to anvil shears for surgical purposes, particularly for laparoscopic operations, with an anvil fixed to the distal end of an instrument tube and a blade pivotably fitted to the anvil. The blade is pivotable against the anvil by means of an operating rod that is longitudinally displaceable in the instrument tube. Handle parts are provided that move against one another with a closing movement that is transferred by the operating rod to the blade.
In modern minimum invasive surgery the instruments required for the operation are introduced through trocar cannulas into the interior of the body, e.g. into the abdominal cavity and are guided under the control of an also introduced endoscope or using X-ray observation and actuated for the individual operating steps. Such operating techniques are e.g. used in laparoscopic cholecystectomy and apendectomy, as well as in orthopedic surgery, e.g. operations on the knee joint. Use is inter alia made of shears introducible through trocar cannulas for cutting vessels, fibre bundles and tendons. An optimum cutting action is necessary particularly when cutting through hard and fibrous tissue, so that the disection takes place in one cut using a blade closing movement, because several movements on the part of the blade and the instrument can cause traumatization of the surrounding tissue. In addition, the performance of a precise cut under endoscopic conditions is complicated, if the shears have to be closed several times with an obstinate material for cutting. For the surgeon it is a complicated, time-consuming task to fix the shears to the same cutting point a number of times, as a result of the restricted observation conditions, which endoscopically only allow a bidimensional observation of the operating area.